Biometric key including a textured ceramic cover

ABSTRACT

An electronic device is provided, the electronic device having a keyboard including a biometric input device. The biometric input device may be a biometric key or button. A cap of a biometric key or button may include a textured ceramic cover, such as a textured sapphire cover. The cap may further include a rear decorative coating and a front antireflective coating disposed on or over the textured ceramic cover. The cap may have one or more visual and or tactile properties which resemble those of an adjacent key of the keyboard.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation patent application of U.S. patentapplication Ser. No. 16/812,297, filed Mar. 7, 2020 and titled“Biometric Key Including a Textured Ceramic Cover,” which is anonprovisional patent application of and claims the benefit of U.S.Provisional Patent Application No. 62/933,839, filed Nov. 11, 2019 andtitled “Biometric Key Including a Textured Ceramic Cover,” thedisclosures of which are hereby incorporated herein by reference intheir entireties.

FIELD

The described embodiments relate generally to electronic devicesincluding a biometric input device, such as a biometric key or button.More particularly, the present embodiments relate to an electronicdevice with a biometric input component which is provided as part of akeyboard and which includes a textured ceramic cover.

BACKGROUND

An electronic device may include one or more input components. Forexample, an input component may have the form of a button or key whichmay be pressed to activate one or more functions or operations of theelectronic device. In some cases, a button or key may include abiometric sensor which can restrict control of (and/or access to) anassociated function or operation of the electronic device.

SUMMARY

Biometric keys and buttons including textured ceramic covers aredisclosed herein. The biometric key or button may be part of a keyboardof an electronic device and typically includes a biometric sensor whichmay be used to control and/or limit access to a function or operation ofthe electronic device to one or more authorized users. For example, thebiometric sensor may be a fingerprint sensor and the biometric buttonmay be a power button or key. The keyboard typically also includes keyswhich do not include a biometric sensor. Electronic devices includingbiometric keys or buttons are also disclosed herein.

A biometric key or button may include a cap which defines an inputsurface and which includes the textured ceramic cover. Other keys of thekeyboard may have a polymeric keycap which in some cases may be aplastic keycap. In some embodiments, the cap of the biometric key orbutton is configured to have a visual and/or tactile property which issimilar to that of the polymeric keycap. For example, the ceramic covermay be textured and coated as described herein to obtain the desiredvisual and/or tactile property. In some cases, a front surface of thecap may have a color, gloss, reflective haze, and/or reflectance whichis similar to that of an adjacent polymeric keycap. The cap and thetextured ceramic cover may each be configured to provide a desiredvisual and/or tactile property to the biometric key or button withoutsubstantially degrading the performance of the biometric sensor.

In some embodiments, one or more textures of the ceramic cover may beconfigured to provide a matte appearance and/or a relatively low glosslevel to the cap. For example, the gloss level of the cap may be lowerthan that of a polished ceramic cover. The textured ceramic cover istypically light transmissive and may be substantially transparent. Insome cases, the textured ceramic cover may be formed of a singlecrystal, such as single crystal alumina (e.g., sapphire). In some cases,the textured ceramic cover defines a front surface, a side surface, anda curved surface (alternately, a curved edge) which extends from thefront surface to the side surface.

The cap may also include one or more coatings on or over one or moresurfaces of the textured ceramic cover. In some embodiments, the cap mayinclude a coating on or over a rear surface of the textured ceramiccover which contributes to the desired color and/or opacity of the cap.When the textured ceramic cover is substantially light transmissiveand/or transparent, the coating on the rear surface of the cap may beconfigured to absorb one or more wavelengths of visible light andthereby help to provide a desired color to the cap. For example, thecoating on the rear surface may help to provide a dark color to the cap.

In some embodiments, the cap may include one or more coatings on or overa front surface of the textured ceramic cover. For example, a coating onthe front surface of the cap may be configured to reduce the amount oflight reflected from the cap and thereby act as an anti-reflectioncoating. In some cases, the anti-reflection coating may also contributeto the perceived color of the cap.

The disclosure provides a computing device comprising an upper portioncomprising an upper housing and a display positioned in the upperhousing and a lower portion comprising a lower housing coupled to theupper portion by a hinge, the lower portion including a keyboard. Thekeyboard comprises an array of keys, each key of the array of keyshaving a plastic keycap, and a biometric power button positionedadjacent to one or more keys of the array of keys. The biometric powerbutton comprises a sapphire cover, an inorganic multilayer coatingdisposed on a rear surface of the sapphire cover, a biometric sensorpositioned below the sapphire cover, and a switch positioned below thebiometric sensor. The sapphire cover defines a textured front surfaceand a rounded edge extending from the textured front surface to a sidesurface.

The disclosure further discloses a computing device comprising an upperportion comprising an upper housing and a display positioned within theupper housing and a lower portion comprising a keyboard and a lowerhousing rotatably coupled to the upper housing. The keyboard includes aset of keys, each key of the set of keys including a keycap formed of apolymer material and a biometric input key. The biometric input keycomprises a textured cap comprising a transparent cover formed ofalumina, a biometric sensor positioned below the transparent cover, andan electromechanical switch positioned below the biometric sensor andconfigured to actuate in response to a press on the biometric input key.The transparent cover defines a front surface including a set of surfacefeatures configured to diffusely reflect light from the front surface, aside surface, and a curved surface extending between the front surfaceand the side surface. The textured cap further comprises a first coatingcovering the front surface and comprising a plurality of inorganicdielectric layers configured to cause destructive interference betweenlight reflected from the first coating and light reflected from thefront surface of the transparent cover and a second coating covering arear surface of the transparent cover and configured to absorb visiblelight.

In addition, the disclosure provides a computing device comprising akeyboard comprising a biometric button and a set of keys. The biometricbutton comprises a cap including a sapphire cover, an anti-reflectioncoating disposed over the front surface of the sapphire cover andcomprising a plurality of inorganic dielectric layers, and an opticallydense coating disposed over a rear surface of the sapphire cover andcomprising a plurality of inorganic dielectric layers and a plurality ofmetal layers. The biometric button further comprises an electricallyconductive support positioned below and coupled to the cap, a biometricsensor positioned below the cap, and a switch positioned below thebiometric sensor. The sapphire cover defines a front surface having afirst texture configured to provide a first matte appearance, a sidesurface; and a curved edge between the front surface and the sidesurface, the curved edge having a second texture. Each key of the set ofkeys includes a polymeric keycap having a second matte appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like elements.

FIG. 1A shows an example electronic device including a biometric inputcomponent.

FIG. 1B shows a detail view of the biometric input component of FIG. 1A.

FIG. 1C shows another example of an electronic device including abiometric input component.

FIG. 1D shows a detail view of the biometric input component of FIG. 1C.

FIG. 2A shows an exploded view of a biometric input component includinga spring plate.

FIG. 2B shows an exploded view of a biometric input component includinga scissor mechanism.

FIG. 3 shows a cross-section view of a biometric input component.

FIG. 4A shows another cross-section view of a biometric input component.

FIG. 4B shows movement of the biometric input component of FIG. 4A inresponse to a downward force.

FIG. 5A shows a top view of a cap for a biometric input component.

FIG. 5B shows a side view of a cap for a biometric input component.

FIG. 6A shows a partial cross-section view of a cap for a biometricinput component.

FIG. 6B shows a detail view of the cap of FIG. 6A.

FIG. 7A shows a detail cross-section view of the cap of FIG. 6A.

FIG. 7B shows a detail cross-section view of the cap of FIG. 7A.

FIG. 8 shows another detail cross-section view of the cap of FIG. 6A.

FIG. 9 shows a flow chart of a process for making a textured cap of abiometric input component.

FIG. 10 shows a block diagram of a sample electronic device that canincorporate a biometric input component with a textured cap.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred implementation. To the contrary, the described embodimentsare intended to cover alternatives, modifications, and equivalents ascan be included within the spirit and scope of the disclosure and asdefined by the appended claims.

The following disclosure relates to an electronic device including abiometric input component, such a biometric key or button. The biometricinput component may include a cap which defines an input surface for thebiometric input component and which includes a textured ceramic cover.In some cases, the cap of the biometric input component may beconfigured to have a visual and/or tactile property similar to that ofan adjacent keycap largely formed of a different material (e.g., apolymer material). For example, the front surface of the cap may have acolor, gloss, reflective haze and/or reflectance which resembles that ofthe adjacent keycap. The ceramic cover may be textured and coated asdescribed herein to obtain the desired visual and/or tactile property.

Each of the cap and the textured ceramic cover may be positioned overthe biometric sensor. In addition, each of the cap and the texturedceramic cover may be configured so that they do not substantiallyinterfere with the operation of the biometric sensor. For example, thetexture of the ceramic cover and the composition and thickness of anycoatings applied to the textured ceramic cover may be configured so thatthey do not substantially interfere with the operation of the biometricsensor. The cap typically has a texture due at least in part to thetexture of the ceramic cover and any coatings applied on or over thefront surface of the textured ceramic cover. The cap may therefore bereferred to herein as a textured cap.

In some embodiments, one or more textures of the ceramic cover may beconfigured to provide a matte appearance and/or a relatively low glosslevel to the cap. Typically a gloss level of the cap is lower than thatof a polished ceramic cover. For example, a front surface of thetextured ceramic cover may define a texture configured to provide agloss level which resembles that of an adjacent keycap. In addition, acurved surface which extends from the front surface to a side surface ofthe ceramic cover may define a texture configured to provide a glosslevel similar to that of the front surface. At least one surface of theceramic cover may be configured to provide a specified level ofreflective haze or extent of diffuse reflection.

In some cases, a texture of the front surface of the ceramic cover isconfigured to diffusely reflect incident light. The surface features maydefine any of a range of shapes or configurations which can diffuse orscatter incident light. Surface textures, surface features, androughness parameters are described in further detail with respect toFIGS. 6A-8 and that description is generally applicable herein.

In some cases, the front surface of the ceramic cover defines a firsttexture and the curved surface defines a second texture. The firsttexture may include a first set of surface features and the secondtexture may include a second set of surface features. In some cases, thefront surface and the curved surface may be textured by differentmethods, so that the first texture and the second texture need not beidentical. However, the first texture and the second texture may besimilar enough to provide similar visual and/or tactile properties tothe textured cap. For example, each of the first set of surface featuresand the second set of surface features may be configured to diffuselyreflect incident light. In addition, the first texture and/or the secondtexture may be controlled so that the front surface and/or the curvedsurface is not overly rough.

In some embodiments, the cap includes a coating on or over a rearsurface of the textured ceramic cover which contributes to the desiredcolor and/or opacity of the cap. When the ceramic cover is substantiallylight transmissive and/or transparent, the coating on the rear surfacemay be configured to absorb one or more wavelengths of visible light andthereby help to provide the desired color to the cap. The color of thecap may be similar to that of an adjacent keycap. The coating may alsobe configured so that it does not substantially interfere with theperformance of the underlying biometric sensor. In some embodiments, thecoating on the rear surface is an inorganic multilayer coating, ratherthan a conventional paint coating or other polymer-based decorativelayer. Inorganic multilayer coatings are described in further detailwith respect to FIGS. 6A-6B and that description is generally applicableherein.

In some embodiments, the cap may include one or more coatings on or overa front surface of the textured ceramic cover. For example, a coating onthe front surface of the cap may be configured to reduce the amount oflight reflected from the cap and thereby act as an anti-reflectioncoating. In some cases, the anti-reflection coating may also contributeto the perceived color of the cap. The one or more coatings over thefront surface of the textured ceramic cover may be configured to have adurability suitable for use on an input surface of the biometric inputcomponent.

In some embodiments, an anti-smudge coating may be applied over ananti-reflection coating. Anti-reflection coatings and anti-smudgecoatings are described in further detail with respect to FIG. 7B andthat description is generally applicable herein. Typically, the capincludes a combination of one or more coatings on or over the texturedfront surface and one or more coatings on or over the rear surface ofthe ceramic cover.

The biometric input component typically includes other components inaddition to the textured cap and the biometric sensor. For example, thebiometric input component may include a switch, such as anelectromechanical switch. Typical components of the biometric inputcomponent are described in further detail with respect to FIGS. 1A-4 and10 and that description is generally applicable herein.

These and other embodiments are discussed below with reference to FIGS.1A-10 . However, those skilled in the art will readily appreciate thatthe detailed description given herein with respect to these figures isfor explanatory purposes only and should not be construed as limiting.

FIG. 1A shows an example electronic device 100 including a biometricinput component 146 which includes a textured ceramic cover. Thebiometric input component may be a biometric power button or key.Alternately the biometric input component may be a biometric button orkey which controls another function of the electronic device.

As shown in FIG. 1A, the electronic device 100 is a notebook computingdevice (alternately, a notebook) or a laptop computing device(alternately, a laptop). In additional embodiments, the electronicdevice 100 may be a mobile telephone (alternately, a mobile phone), atablet computing device (alternately, a tablet), a tablet computingdevice with a keyboard, a portable media player, a wearable device, oranother type of portable electronic device.

FIG. 1A shows the electronic device 100 in an open configuration. Asshown in FIG. 1A, the electronic device 100 includes a first or upperportion 102 and a second or lower portion 104. Typically the firstportion 102 and the second portion 104 are coupled. As shown in FIG. 1A,the electronic device may include a coupling portion 106. In some cases,the first portion 102 and the second portion 104 may be rotatably orpivotably coupled, such as by a hinge within coupling portion 106.Rotatable coupling of the first portion 102 and the second portion 104allows the first portion 102 to be rotated towards the second portion104 to place the electronic device 100 in a closed configuration.However, in additional embodiments, the second portion 104 may becoupled to the first portion 102 in a different manner and/or may beremovable with respect to the first portion 102.

The electronic device 100 further includes a first or upper housing 112and a second or lower housing 114. The first housing 112 is part of thefirst portion 102 and the second housing 114 is part of the secondportion 104. The first housing 112 at least partially encloses a display122. The display 122 may be a primary display for the electronic device.The display may be a liquid-crystal display (LCD), a light-emittingdiode (LED) display, a LED-backlit LCD display, an organiclight-emitting diode (OLED) display, an active layer organiclight-emitting diode (AMOLED) display, and the like. The display may becovered by a transparent cover, which may comprise one or more glass,ceramic, or polymer layers.

The lower portion 104 includes a keyboard 132. As shown in FIG. 1A, thekeyboard 132 includes the biometric input component 146 and a set ofkeys 142. As previously discussed, the biometric input component mayhave a cap (e.g., cap 156 of FIG. 1B) which is configured to have one ormore visual and/or tactile properties which are similar to that of anadjacent keycap (e.g., keycap 152 of FIG. 1B). For example, the frontsurface of the cap 156 may be configured to have a color, gloss,reflective haze and/or reflectance which resembles that of the adjacentkeycap 152.

Typically, the keycap 152 is a polymeric keycap and the ceramic cover ofthe cap 156 is textured and coated to obtain the one or more visualand/or tactile properties which are similar to that of a polymerickeycap 152. For example, the keycap 152 may be translucent or opaque andmay be textured to provide a low gloss appearance. In addition, a bodyof the keycap 152 (e.g., the structure supporting or surrounding asymbol or glyph provided on the keycap) may have a color imparted by adye or pigment in a polymer material of the keycap. In some cases, thekeycap 152 may have a dark color that has a L* value from about 20 toabout 40, from about 20 to about 35, or from about 20 to about 30.

As referred to herein, a polymeric keycap may substantially comprise apolymer material but may also include a dye, a pigment, a metal, orother marking material applied to an input surface of the keycap to forma marking such as a symbol or glyph on the keycap. A polymeric keycapmay be substantially formed from a polymer material. A polymer materialincludes a polymer, but may also include additives such as a colorant(e.g., a dye or a pigment dispersed within a body of the keycap) and/orother additives to facilitate manufacturing of the keycap and/or toproduce the desired properties of the keycap. The polymer material maybe a thermoplastic polymer material (also referred to as a plasticherein) and the polymeric keycap may therefore be referred to as aplastic keycap. As an example, the polymer material of the keycap maycomprise acrylonitrile butadiene styrene (ABS), polybutyleneterephthalate (PBT), polyoxymethylene (POM), and the like.

The biometric input component 146 may be a biometric power button or keyor another type of biometric button or key. A biometric key may also bereferred to herein as a biometric input key. In the example of FIG. 1Athe biometric input component 146 is positioned between the set of keys142 and the coupling portion 106, but it should be understood that thebiometric input component 146 may be located in another position of thesecond portion 104, such as amongst the set of keys 142. The set of keys142 may define an array and/or multiple rows of keys. Each of the keys142 may be depressible. Each of the keys 142 may also have a keycap 152(shown in FIG. 1B). The keyboard 132 may also include a key 144positioned between the set of keys 142 and the coupling portion 106. Thekeyboard 132 may be positioned in a recessed portion 116 of the secondhousing 114. In some cases, a user of the electronic device 100 may usethe keyboard 132 to interact with a user interface presented, at leastin part, on the display 122.

The biometric input component 146 may include a biometric sensor (shownin FIGS. 2 and 3 ) which can be used to authenticate the identity of auser interacting with the biometric input component 146, such as byapplying force to a cap 156 (shown in FIG. 1B) of the biometric inputcomponent 146. The biometric sensor may be used to restrict access to anelectronic device feature or operation associated with the biometricinput component 146 to one or more authenticated users. Therefore thebiometric input component 146 may also be referred to as a“restricted-access” button or key. A function or operation requiringuser authentication may be referred to as a “restricted function” or a“restricted operation.” In some cases, one or more functions associatedwith the biometric input component 146 may be restricted functions whileother functions of the biometric input component 146 may be unrestrictedfunctions (which are not restricted to an authenticated user).

In some embodiments, the biometric input component 146 may serve as apower button or key. In some cases, the biometric input component 146may serve as a multimodal power button or key. For example, a multimodalpower button or key may be configured to change a power state of theelectronic device 100 and/or a power state of the keyboard 132.

When the biometric input component 146 functions as a restricted-accessbutton, one or more functions associated with a biometric inputcomponent 146 may be restricted functions that can only be performed byan authorized user. For example, turning on or off the electronic devicemay be a restricted function that can only be performed by an authorizeduser or group of users. In some cases, when the biometric inputcomponent 146 is pressed, an image of a fingerprint may be obtained andcompared to the previously-obtained fingerprint images of the limitedset of authorized users. If it is determined that the obtained imagematches that of one of the previously-obtained fingerprint images of thelimited set of authorized users, then the electronic device may performthe operation associated with the biometric input component 146 (e.g.,turn on, turn off, enter a standby state, and so on). Alternatively, ifit is determined that the obtained image does not match that of one ofthe previously-obtained fingerprint images of the limited set ofauthorized users, the electronic device may not perform the operationassociated with the biometric input component 146. In some cases, theelectronic device may notify the user that access is denied. In othercases, the electronic device may not respond in any manner.

In some embodiments, when a user presses the biometric input component146, the keyboard 132 can send a signal to the electronic device 100that the button (or key) has been pressed. In response thereto, theelectronic device 100 may transition to a different power state such as,but not limited to: an on power state, an off power state, a standbypower state, a low power state, or any other suitable power state. Oneor more functions of the biometric input component 146 may be restrictedfunctions whereas other functions of the biometric input component 146may be unrestricted functions. More specifically, the operation oftransitioning between various power states, performed by the electronicdevice 100 in this example, may be restricted actions or may beunrestricted actions. In one example, a transition to an on power statefrom an off power state may be an unrestricted action whereas atransition to an off power state from an on power state may be arestricted action. In another non-limiting phrasing, the electronicdevice 100 may permit any user to turn on the electronic device 100 oranother associated electronic device, while permitting only certainusers to turn off the electronic device 100.

When a user presses the biometric input component 146, the electronicdevice 100 may first determine whether the action or function sought tobe performed by the electronic device 100 or the keyboard 132 is arestricted action or an unrestricted action. If the action is arestricted action, then an image of a fingerprint may be obtained by thefingerprint sensor of the biometric input component 146. The obtainedfingerprint image may then be compared to each fingerprint image (ortemplates) of a set of previously-obtained fingerprint images (ortemplates) to determine whether the user who pressed the biometric inputcomponent 146 is authorized to perform the requested function. In somecases, the electronic device may utilize a fingerprint data (such as animage) as one of multiple factors to authenticate a user. Alternatively,if the action is an unrestricted action, the electronic device 100 mayperform the action without first obtaining a fingerprint image.

In further embodiments, the biometric input component 146 can beconfigured to operate in a different manner. For example, the biometricinput component 146 may be configured to record and/or log the identityof the last user to touch the biometric input component 146 and/orinformation related to unrecognized fingerprints obtained by thebiometric input component 146.

In some cases, the operation of obtaining a fingerprint image andcomparing the fingerprint to a set of known images may be performed bythe electronic device 100. In some examples, this operation may beperformed within the biometric input component 146, such as by aprocessor or circuitry disposed within the biometric input component146. In still further examples, this operation may be performed at leastin part by a processor or circuitry coupled to the biometric inputcomponent 146.

After a fingerprint obtained by the fingerprint sensor of the biometricinput component 146 is recognized, one of a variety of operations may beperformed by the electronic device 100, the keyboard 132, or thebiometric input component 146. For example, in one embodiment, after afingerprint image obtained by the fingerprint sensor of biometric inputcomponent 146 is recognized, the keyboard 132 may send a signal to theelectronic device 100 instructing the electronic device 100 to performthe requested action. In another embodiment, after a fingerprint imageobtained by the fingerprint sensor of the biometric input component 146is recognized, the keyboard 132 may send an encrypted signal, a securitycertificate, a password, or other information to the electronic device100 informing the electronic device 100 that the keyboard 132 hasidentified a user. The electronic device 100 may analyze the informationreceived to determine whether the user is authorized to perform therequested task.

In further embodiments, the electronic device 100 and/or the keyboard132 can utilize the fingerprint sensor separately from the buttoncontaining the sensor. For example, fingerprint image data may beobtained from a user of the electronic device 100 without a press of thebutton containing the fingerprint sensor. In still other cases, thefingerprint sensor may be configured to image a fingerprint of the userseparately from activation of the respective button or associatedaction. More specifically, the button may have a default function thatcan be performed by the electronic device 100 that may be changed,updated, augmented, or enhanced only after a fingerprint image is laterrecognized. For example, in these embodiments, a fingerprint image maybe taken after the button is fully pressed. As referred to herein, afingerprint “image” does not need to be a visual representation of thefingerprint, but may be an array of sensor values that provides asignature that corresponds to the fingerprint, such as a two-dimensionalarray of sensor values that provides a signature that corresponds to thefingerprint.

In many cases, the electronic device 100 and/or the keyboard 132 canrequire both a full button press and an authenticated fingerprint inorder to perform a task. For example, if the biometric input component146 is a power button (or key), a full press of the cap by anauthenticated user may be required to turn on the electronic device 100or the keyboard 132. In this manner, two different types of input arerequired to power on the electronic device.

In further embodiments, the electronic device 100 and/or the keyboard132 can utilize the fingerprint sensor within the biometric inputcomponent 146 in a manner disassociated from the various functionsand/or operations of the biometric input component 146. For example, theelectronic device 100 may periodically request that a user of theelectronic device 100 or the keyboard 132 authenticate the user'sidentity by placing the user's fingertip on the biometric inputcomponent 146. The electronic device 100 may request that a user of theelectronic device 100 authenticate his or her identity in order to,without limitation: grant access to an application or program executedby the electronic device 100, grant access to a feature of anapplication or program executed by the electronic device 100, completean electronic purchase, access confidential and/or private informationstored on or otherwise accessible to the electronic device 100, accesssystem-level files and/or directories stored on or otherwise accessibleto the electronic device 100, approve or deny the establishment of acommunication link between the electronic device 100 and another localor remote electronic device, apply settings associated with a particularuser to the electronic device 100 or an application or program operatingthereon, and so on.

As shown in FIG. 1A, the electronic device 100 further includes an inputdevice 148. The input device 148 may include a touch-sensitive display.In some cases, the touch-sensitive display may be used to present a setof indicia that corresponds to a set of commands or functions that maybe selected by a user of the electronic device 100. The input device 148may be responsive to a user touch, allowing selection by a user of oneor more of the set of commands or functions. The touch-sensitive displaymay be generally rectilinear in form and may have a front surface 158(shown in FIG. 1B). The input device 148 may be positioned above thetopmost set of keys of the keyboard 132, in the place of a traditionalfunction row on a conventional keyboard. In some cases, the input device148 can be used to perform the same functionality as a traditionalfunction row, as well as perform an expanded and diverse set of commandsand functions as described herein.

An input device 148 including a display can be configured to display aset of visual indicia that corresponds to an input mode of the keyboard132 of the electronic device 100. For example, the input device 148 maybe configured to display a set of virtual keys. The indicia on thedisplay may correspond to one or more of the following: ahardware-dependent input mode used to control one or more devices orhardware elements of the keyboard 132 or the electronic device 100; asoftware-dependent input mode used to control one or more aspects of asoftware program being executed on the electronic device 100; auser-defined mode that is configurable by a user of the electronicdevice 100 or the keyboard 132; and other input mode examples which aredescribed herein. The display of the input device 148 may be used topresent a set of static indicia, one or more animated indicia, or acombination of static and animated indicia.

The display of input device 148 may be integrated with one or more touchsensors and/or force sensors that are configured to detect variouscombinations of user touch and force input on the front surface 158 ofthe input device 148. The touch and/or force sensors may provide atouch-sensitive surface that is configured to detect the location of atouch, a magnitude and/or direction of force applied, and/or a movementof the touch along the input device 148. The touch and/or force sensorsmay be used separately or in combination to interpret a broad range ofuser inputs such as, but not limited to: touch-based gestures,force-based gestures, touch patterns, tap patterns, single-fingergestures, multi-finger gestures, multi-force gestures, and so on.

As shown in FIG. 1A, the electronic device 100 further includes a forceand/or touch sensitive trackpad 138 which also functions as an inputcomponent. The electronic device typically includes one or moreadditional components, such as a memory, a processor, control circuitry,a battery, an output device, a communication port, an accessory (such asa camera), and an additional sensor. One or more of these additionalcomponents may interface or interoperate, either directly or indirectly,with the biometric input component 146. The description of electronicdevice components provided with respect to FIG. 10 is generallyapplicable herein, and, for brevity, is not repeated here.

FIG. 1B shows a detail view of the biometric input component 146 of FIG.1A (e.g., of area A-A in FIG. 1A). As shown in FIG. 1B, the biometricinput component 146 includes a cap 156 which defines an input surface ofthe biometric input component 146. In addition, the key 142 includes akeycap 152 which defines an input surface of the key 142.

The cap 156 of the biometric input component 146 may include a ceramiccover. A cap for a biometric input component, such as cap 156, may alsobe generally referred to herein as a cover assembly. In some examples,the ceramic cover may substantially or essentially consist of singlecrystal alumina, e.g., single crystal alpha alumina or sapphire. The cap156 may have a texture due at least in part to the texture of theceramic cover and may thus be referred to as a textured cap. Examples ofceramic covers are shown in the cross-section views of FIGS. 6A-8 . Thedescription of ceramic covers provided with respect to FIGS. 6A-8 isgenerally applicable herein, and, for brevity, is not repeated here.

The cap 156 of the biometric input component 146 may be textured to helpprovide a desired visual and/or tactile property to the cap. In someembodiments, the cap 156 includes one or more coatings applied to thefront side of a textured ceramic cover and one more coatings applied tothe rear side of the textured ceramic cover. These front and rearcoatings may also contribute to one or more of the desired visual and/ortactile properties of the cap. The description of front and rearcoatings provided with respect to FIGS. 6A-8 is generally applicableherein, and, for brevity, is not repeated here.

In some embodiments, the cap 156 may be configured to have one or morevisual properties which resemble those of the input surface of anotherinput component, such as the key 142, the key 144, and/or the inputdevice 148. In some cases, a front surface of the cap 156 may beconfigured to have one or more visual properties which resemble those ofa front surface of the keycap 152. For example, the front surface of thecap 156 may have a color, gloss, reflective haze and/or reflectancewhich resembles that of the front surface of another input component,such as the front surface of the keycap 152. The textured ceramic covermay have a visual and/or tactile property which differs from that of aconventionally polished ceramic cover. Texture and visual properties ofthe cap 156 are discussed in greater detail with respect to FIGS. 6A-8 .The description provided with respect to FIGS. 6A-8 is generallyapplicable herein, and, for brevity, is not repeated here.

In some cases, the front surface of the cap 156 may be aligned andsubstantially coplanar with the front surface of another inputcomponent. For example, the front surface of the cap 156 may be alignedand substantially coplanar with the front surface of the keycap 152. Insome cases, the front surface of the cap 156 may be positioned below afront surface 118 of the second housing 114, so that the front surfaceis recessed with respect to the front surface 118. However, the frontsurface of the cap 156 is typically elevated with respect to the bottomof the recess 116. The front surface of the cap 156 may also be referredto herein as an exterior surface, as it faces away from the interior ofthe second portion 104 of the electronic device.

In some cases, the cap 156 of the biometric input component 146 isspaced apart from the cap 152 of an adjacent key 142. For example, thespacing or gap G between the cap 156 and the cap 152 of the adjacent key142 may be from about 0.5 mm to about 5 mm or from about 1 mm to about 5mm. In addition, the cap 156 of the biometric input component 146 may bespaced apart from the front surface 158 of the input device 148 and thisspacing or gap may be from about 0.5 mm to about 5 mm or from about 1 mmto about 5 mm.

FIG. 1C shows another example of an electronic device 101 including abiometric input component 146, which may be a biometric button or key.As previously described with respect to FIGS. 1A-1B, a cap 156 of thebiometric input component 146 comprises a textured ceramic cover and maybe configured to have a visual and/or tactile property similar to thatof an adjacent keycap of the electronic device.

The electronic device 101 does not include the input device 148 ofelectronic device 100, but instead the keyboard 133 includes additionalkeys 144. At least some of the keys 144 may be “function keys” which areassociated with one or more functions of the electronic device 101. Eachof the first portion 102, the second portion 105, the coupling portion106, the first housing 112, the second housing 115, the depression 117,the front surface 119, the display 122, the keyboard 133, force and/ortouch sensitive trackpad 138, the keys 142 and 144, and the biometricinput component 146 may be similar to the respective elements 102, 104,106, 112, 114, 116, 118, 122, 132, 138, 142, 144, and 146 previouslydescribed for electronic device 100 and, for brevity, that descriptionis not repeated here.

FIG. 1D shows a detail view of the biometric input component 146 of FIG.1C (e.g., of area D-D in FIG. 1C). As was previously described withrespect to FIGS. 1A and 1B, the cap 156 of the biometric input component146 may be configured to have one or more visual properties whichresemble those of the key caps 152 of the keys 142. In addition oralternately, the cap 156 may be configured to have one or more visualproperties which resemble those of the key caps 154 of the keys 144.

In some cases, the cap 156 of the biometric input component 146 isspaced apart from the cap 154 of an adjacent key 144. The spacingbetween the cap 156 and the key cap 154 of an adjacent key 144 may besimilar to the spacing between the cap 156 and an adjacent key 142previously described with respect to FIG. 1B.

FIG. 2A shows an exploded view of elements of a biometric inputcomponent 246 including a biometric sensor 254 and a cap 256 comprisinga textured ceramic cover. The biometric input component 246 may be abiometric button or key. The cap 256 of the biometric input component246 may be configured to have a visual and/or tactile property similarto that of an adjacent keycap of the electronic device. As shown in FIG.2A, the biometric input component 246 includes a cap 256, a support 255,the biometric sensor 254, a circuit layer 253, a switch 252, and a keyassembly 251. The key assembly 251 defines a spring plate. The cap 256,the support 255, the biometric sensor 254, the circuit layer 253, theswitch 252, the key assembly 251, and fasteners 273 and 274 may becollectively referred to as a “button assembly” or a “key assembly.” Thebiometric input key 246 may be an example of the biometric input key 146or any other biometric input key described herein.

FIG. 2A also shows a portion of a second housing 214. The second housing214 defines a top surface 218, a first recess 216, a second recess 226,and holes 224. The button assembly may be configured to couple to thesecond housing 214 so that at least some of the elements of the button(or key) assembly are accommodated within the recess 226. As indicatedin FIG. 2A, the cap 256, the biometric sensor 254, the circuit layer253, and the switch 252 are positioned on an exterior side of thehousing 214 while the key assembly 251 is positioned on an interior sideof the housing 214. The protruding portions 266 of the support 255 maypass through the holes 224 and may be fastened to the key assembly 251by the fasteners 274. The fasteners 273 may fasten the key assembly 251to the second housing 214. The fasteners 273 may pass through holes 263in the key assembly 251 while the fasteners 274 may pass through holes264 in the key assembly 251.

The biometric input component 246 includes a cap 256. As previouslydescribed with respect to FIGS. 1A-1B, the cap 256 may include a ceramiccover, such as a sapphire cover, one or more coatings applied to thefront side of the cover and one or more coatings applied to the rearside of the cover. The cap 256 may be configured to provide one or moredesired visual and/or tactile properties. The description of ceramiccovers and caps provided with respect to FIGS. 1B and 5-8 is generallyapplicable herein, and, for brevity, is not repeated here.

As shown in FIG. 2A, the biometric input component 246 further includesa support 255. The cap 256 is typically coupled to the support 255, asshown in FIG. 3 . For example, the cap 256 may be directly coupled tothe support 255 by an adhesive. The textured ceramic cover included inthe cap 256 is also typically coupled to the support 255. In otherembodiments, the support 255 may have a different form or may beomitted.

As shown in FIG. 2A, the support 255 may include a frame portion 265 andmultiple protruding features (e.g., bosses) 266 coupled to the frameportion 265. The frame portion 265 may define a central opening 267 andthe cap 256 may span the central opening 267. In the examples of FIGS. 2and 3 , an entirety of the frame portion 265 is positioned below the cap256. In some cases, the frame portion 265 and the protruding features266 may be formed as an integral piece. The support 255 may be formed ofan electrically conductive material, such as a metal (including a metalalloy).

As previously described, the biometric input component 246 includes abiometric sensor 254. The biometric sensor 254 may be positioned atleast partially within central opening 267 defined by the frame portion265. The biometric sensor 254 may be directly coupled to the cap 256,such as by an adhesive.

The biometric sensor 254 may be configured to obtain one or more formsof biometric data. In some embodiments, the biometric sensor 254 maycapture one or more fingerprint images and may therefore be referred toherein as a “fingerprint sensor.” As used herein, the term “image”encompasses both an actual graphical image of a fingerprint (or portionthereof) as well as a data set representing certain aspects of afingerprint, such as a mathematical construct derived from aspects of auser's fingerprints. The biometric sensor 254, alone or in combinationwith processing circuitry, may produce a two-dimensional representationof the fingerprint, which may be a two-dimensional representation of aportion of the fingerprint.

A fingerprint sensor can be implemented with any suitable fingerprintimaging or detection technology including, but not limited to,capacitative sensing, optical sensing, electrical impedance sensing,acoustic impedance sensing, and so on. In some embodiments, thefingerprint sensor may include an array of electrodes such ascapacitative sensors, electrical impedance sensors, ultrasonic sensors,and the like. As an example, the fingerprint sensor may becapacitance-based and the biometric input component may be configured sothat one or more capacitative sensors/electrodes can capacitativelycouple to the finger of a user through the cap 256. For example, theceramic cover of the cap 256 may be suitably thin, such as from 100microns to 750 microns, from 100 microns to 400 microns, or from 200microns to 500 microns. In additional embodiments, the biometric datamay alternately or additionally include heart rate, blood oxygenation,respiration rate, medial arterial pressure, galvanic skin response, veinpatterns, and the like. The description of the biometric sensor 254 isgenerally applicable to the biometric sensors described herein.

As shown in FIG. 2A, the biometric input component 246 also includes acircuit layer 253. The circuit layer 253 may be coupled to the biometricsensor 254, such as by an adhesive. The circuit layer 253 may include aflexible circuit. Further, the circuit layer 253 may be configured tosend a signal to and/or receive a signal from the biometric sensor. Insome cases, the circuit layer 253 may include processing circuitry. Forexample, the processing circuitry may transmit signals to or from thebiometric sensor, may be configured to process a signal from thebiometric sensor, or may connect the biometric sensor 254 to additionalprocessing circuitry. In some cases, the circuit layer is in electricalcommunication with the fingerprint sensor and configured to produce atwo-dimensional representation of features of a fingerprint (an “image”of the fingerprint). In some cases, a power supply may be coupled to thecircuit layer and/or the biometric sensor 254.

The biometric input component 246 further includes a switch 252. In somecases, the switch 252 may be an electromechanical switch such as atactile switch (tact switch). The electromechanical switch may include acompliant and/or biasing component such as a compressible dome, spring,beam, or other structure. For example, the electromechanical switch maybe a dome switch including one or more compressible dome structures. Insome cases, the compliant and/or biasing component (e.g., the compliantcomponent 363 shown in FIG. 3 ) may be provided on an underside of theswitch 252, facing the housing 214. When the biasing componentcollapses, it may complete an electrical circuit, thereby causing theactuation signal to be produced.

More generally, the biometric input component 246 may replace the switch252 with a force sensor. Such a force sensor may provide an electricalresponse which indicates an amount of force applied to the force sensorand/or cap 256. The force sensor may detect the amount of force throughcapacitance force sensing, ultrasonic force sensing, a strain gaugetechnique, an optical technique, a resistance technique, or apiezoelectric technique. In some cases, the force sensor may beconfigured to compare the amount of applied force to multiple thresholdlevels and provide output signals accordingly.

As shown in FIG. 2A, the biometric input component 246 further includesa key mechanism 251 which helps to control downward displacement of thecap 256. The key mechanism 251 can also provide an upward biasing forceto the cap 256. As shown in FIG. 2A, the key mechanism 251 defines aspring plate. The key mechanism 251 may be configured to provide anupward biasing force to the cap 256, as is described in more detailbelow. The key mechanism 251 of FIG. 2A may cooperate with a compliantand/or biasing component (e.g., a collapsible dome) to control movementof the cap 256. Such a compliant and/or biasing component may beprovided as part of the switch 252. The example of FIG. 2A is notlimiting and in additional examples the key mechanism may include ascissor mechanism (as shown in FIG. 2B), a butterfly mechanism, acompliant membrane, a collapsible dome, a spring, or a combination ofthese. Further, in some embodiments, the biometric component input maybe configured to respond to a press on the cap without requiringsignificant travel of the cap.

The key mechanism 251 may be formed of a metal (including a metalalloy), plastic, or like material suitable for providing the biasingforce. For example, the key assembly 251 may be formed of steel,including tempered steel. As shown in FIG. 2A, the key assembly 251 maybe formed as a plate with two oppositely oriented cutout portionsforming two independent “tongues.” However the specific geometry of thekey assembly 251 shown in FIG. 2A is merely an example and otherconfigurations of the key assembly 251 may also be suitable.

As illustrated in FIG. 2A, one portion of the key assembly 251 may becoupled to an interior surface of the housing 214 and another portion ofthe key assembly 251 may be coupled to the cap 256. As shown in FIG. 2A,a central portion 261 of the key assembly 251 may be attached to thehousing 214 using the fasteners 273. The fasteners 273 may pass throughopenings 263 in the key assembly 251. A peripheral portion 262 of thekey assembly 251 may be attached to the protruding portions 266 of thesupport 255 using the fasteners 274. The fasteners 274 may pass throughopenings 264 in the key assembly 251. When force is applied to the cap256, the peripheral portions 262 of the key assembly, which are coupledto the protruding portions 266, may deflect away from the interiorsurface of the housing 214 (as shown in FIG. 4B). In some cases, theprotruding portions 266 may protrude from the holes 224 when force isapplied to the cap 256 (as shown in FIG. 4B). When force is removed fromthe cap 256 (e.g., when a user no longer applies force to the cap), thekey assembly 251 may provide an upward biasing force to return the cap256 to its original position.

FIG. 2B shows an exploded view of elements of a biometric inputcomponent 247 including a biometric sensor 254 and a cap 256 comprisinga textured ceramic cover. The biometric input component 247 may be abiometric button or key. The cap 256 of the biometric input component247 may be configured to have a visual and/or tactile property similarto that of an adjacent keycap of the electronic device. As shown in FIG.2B, the biometric input component 247 includes a cap 256, a support 257,the biometric sensor 254, a circuit layer 253, a key mechanism 258, andswitch 259. The cap 256, the support 257, the biometric sensor 254, thecircuit layer 253, the switch 259, the key mechanism 258, and thesupport plate 279 may be collectively referred to as a “button assembly”or a “key assembly.” The biometric input key 247 may be an example ofthe biometric input key 146 or any other biometric input key describedherein. Each of the cap 256, the biometric sensor 254, the circuit layer253, and the switch 259 may be similar to the respective elements 256,254, 253, and 252 previously described for biometric input component 246and, for brevity, that description is not repeated here.

As shown in FIG. 2B, the key mechanism 258 defines a scissor mechanism.The key mechanism 258 may also cooperate with a compliant and/or biasingcomponent such as a collapsible dome 283 to control movement of the cap256. The compliant and/or biasing component may be provided as part ofthe switch 259. The example of FIG. 2B is not limiting and in additionalexamples the key mechanism may include a spring plate (as shown in FIG.2A), a butterfly mechanism, a compliant membrane, a collapsible dome, aspring, or a combination of these. Further, in some embodiments, thebiometric component input may be configured to respond to a press on thecap without requiring significant travel of the cap.

As shown in FIG. 2B, the key mechanism 258 comprises an external scissormember 265 and an internal scissor member 266. The external scissormember 265 may include retaining features (e.g., retaining features 291and 294) and the interior scissor member 266 may include retainingfeatures (e.g., retaining features 292 and 295) which allow the scissormembers 265 and 266 to be coupled to the frame portion 268 and thesupport plate 279, as described in further detail below. The internalscissor member 266 may also define one or more engagement features whichengage with the external scissor member 265 to allow the internalscissor member 266 to pivot with respect to the external scissor member265. The external scissor member 265 may comprise a correspondingengagement feature, which may be a notch or slot configured to receivethe engagement features. Pivoting of the internal scissor member 266with respect to the external scissor member 265 can change the heightspanned by the scissor mechanism 258.

The internal scissor member 266 may define an opening 276. The opening276 may be configured to receive a compliant component 283 of the switch259 (e.g., a compliant component similar to that of compliant component363 shown in FIG. 3 ). The scissor mechanism 258 is disposed below thecap 256 and is configured to support the cap 256 and the support 257during travel of the cap 256. For example, the height spanned by thescissor mechanism 258 decreases to allow the cap 256 to be presseddownwards and the height spanned by the scissor mechanism increases asthe cap 256 returns to its rest position (e.g., by action of a compliantcomponent). The examples of the external scissor member 265 and theinternal scissor member 266 shown in FIG. 2B are not limiting and eachof the external scissor member 265 and the internal scissor member 266may have a shape and/or size different from that shown in FIG. 2B.

As shown in FIG. 2B, the support 257 may include a frame portion 268.The frame portion 268 may define a central opening 269 and the cap 256may be positioned within and substantially fill the central opening 269.The frame portion 268 may be configured to interface with the externalscissor member 265 and the internal scissor member 266. For example, theframe portion 268 may comprise one more retaining components or features(e.g., retaining feature 281) configured to cooperate with the externalscissor member 265 and the internal scissor member 266. For example, anunderside of the frame portion 268 may include a retaining feature 281configured to pivotally couple a first portion of one of the externalscissor member 265 and the internal scissor member 266 to the frameportion 268. The underside of the frame portion 268 may also beconfigured to allow sliding movement of a second portion of the other ofthe external scissor member 265 and the internal scissor member 266. Inthe example of FIG. 2B, an entirety of the frame portion 268 ispositioned below the cap 256. The support 257 may be formed of anelectrically conductive material, such as a metal (including a metalalloy).

In some cases, one of the external scissor member 265 and the internalscissor member 266 pivotally couple to a support plate 279 and the otherof the external scissor member 265 and the internal scissor member 266is slidably coupled to the support plate 279. For example, the supportplate 279 may include one or more retaining features 284 configured toallow pivotal movement and one or more retaining features 285 configuredto allow sliding movement. In some cases, the switch 259 may be coupledto the support plate 279 and a compliant component provided on an upperside of the switch 259, facing the cap 256. In additional examples, theswitch 259 may be coupled to the support 279 and the compliant componentmay be provided on an underside of the switch 259, facing the thirdhousing 215. The support plate 279 may be positioned below the recess217 of the third housing 215.

FIG. 2B also shows a portion of a third housing 215. The third housing215 defines a top surface 219 and a recess 217. The button assembly maybe configured to couple to the third housing 215 so that at least someof the elements of the button (or key) assembly are accommodated withinthe recess 217.

FIG. 3 shows a cross-section view of a biometric input component 346including a biometric sensor 354 and a cap 356 comprising a texturedceramic cover. The biometric input component 346 may be a biometricbutton or key. The cap 356 of the biometric input component 346 may beconfigured to have a visual and/or tactile property similar to that ofan adjacent keycap of the electronic device. The biometric inputcomponent may be a biometric power button or key or another type ofbiometric input component. FIG. 3 may show an example of the electronicdevice 100 and biometric input component 146 of FIGS. 1A-1B, with thecross-section taken along B-B. The biometric input component 346 iscoupled to a housing 314. The description of biometric input componentsand biometric sensors provided with respect to FIGS. 1A-1D and 2 isgenerally applicable herein and, for brevity, is not repeated here.

As shown in FIG. 3 , the cap 356 is coupled to a front side of thesupport 355 and the switch 352 is coupled to a rear side of the support355. The biometric sensor 354 is coupled to the cap 356 and the circuitlayer 353 is coupled between the biometric sensor 354 and the switch352. In some cases, the coupling may be achieved with an adhesive.

In the example of FIG. 3 , the switch is an electromechanical switchcomprising a compliant component 363. In some cases, theelectromechanical switch may include multiple compliant components. Inthe example, of FIG. 3 , the compliant component 363 is dome-shaped andcontacts a protrusion 315 positioned within the recess 326 of thehousing 314.

The key assembly 351 is attached to an interior surface of the housing314 with fasteners 358. The support 355 may include bosses similar tobosses 266 and additional fasteners similar to fasteners 257 may couplethe support 355 to the key assembly 351 (in a similar fashion as shownin FIGS. 4A-4B). The cap 356, the support 355, the biometric sensor 354,the circuit layer 353, the switch 352 and the key assembly 351 may besimilar to the cap 256, the support 255, the biometric sensor 254, thecircuit layer 253, the switch 252 and the key assembly 251 and, forbrevity, that description is not repeated here.

As shown in FIG. 3 , the cap 356 may define a front surface 372, a sidesurface 374, and a rounded or curved surface 376 extending between thefront surface 372 and the side surface 374. In some embodiments, therounded or curved surface 376 may be referred to as a rounded edge orcorner. In the example of FIG. 3 , the side of the cap 356 generallyaligns with (also, is flush with) a side 378 of the support 355.However, in some cases, a lateral dimension (e.g., L of FIG. 5B) of thecap 356 may be greater than a lateral dimension of the support 355, sothat the side 374 of the cap 356 projects (alternately extends) beyondthe side 378 of the support 355.

Typically, the front surface 372 of the cap 356 is textured. The roundedsurface 376 may also be textured. In some cases, a texture of the frontsurface 372 may be similar to a texture of the rounded surface 376. Thedescription of the textures of the front surface and the rounded surfaceprovided with respect to the detail view of FIGS. 6A-8 is generallyapplicable herein and, for brevity, is not repeated here.

As shown in FIG. 3 , the support 355 is positioned under the cap 356, sothat the cap 356 would be positioned between the support 355 and thefinger of a user. As previously discussed, the support 355 may be formedof an electrically conductive material. As an example, the fingerprintsensor may be capacitance-based and the biometric input component may beconfigured so that the support 355 can also capacitatively couple to thefinger of a user through the cap 356. For example, the textured ceramiccover of the cap may be suitably thin, such as from 100 microns to 750microns, from 100 microns to 400 microns, or from 200 microns to 500microns. In some cases, the support 355 may be coupled to a circuitground. In other cases, a voltage may be applied between the support 355and a circuit ground. The voltage may be a direct current (DC) voltageor an alternating current (AC) voltage. The voltage applied between thesupport 355 and the circuit ground may have a magnitude, a sign, and/ora phase different than a voltage applied between a capacitativesensor/electrode of the biometric sensor and the circuit ground.

FIG. 4A shows another cross-section view of a biometric input component446 including a biometric sensor and a cap 456 comprising a texturedceramic cover. The cap 456 of the biometric input component 446 may beconfigured to have a visual and/or tactile property similar to that ofan adjacent keycap of the electronic device. FIG. 4A may show an exampleof the electronic device 100 and the biometric input component 146 ofFIG. 1A, with the cross-section taken along C-C. The biometric inputcomponent 446 may be a biometric power button or key or another type ofbiometric input component. The biometric input component 446 is coupledto a second housing 414 and is positioned at least partially within arecess 426 of the housing.

The cross-section view of FIG. 4A passes through the protruding portions(bosses) 466 of the support 455 as well as through the frame portion465. Therefore, some components of the button or key assembly which wereshown in FIGS. 2-3 are not visible in the cross-section view of FIG. 4Aas they are hidden by the frame portion 465. For the purposes ofillustration, a compliant member (e.g., a dome) 463 of a switch and aprotrusion 415 from the bottom of the recess 426 are shown with dottedlines.

In a similar fashion as previously described with respect to FIG. 2A, acentral portion 461 of the key assembly 451 may be attached to thehousing 414 using the fasteners 458. A peripheral portion 462 of the keyassembly 451 may be attached to the protruding portions 466 (bosses) ofthe support 455 using the fasteners 457.

FIG. 4B shows movement of the biometric input component 446 of FIG. 4Ain response to a downward force 490. When the downward force 490 isapplied to the cap 456, the compliant component 463 may at leastpartially collapse against the protrusion 415, allowing the cap 456 tomove downwards. In addition, the peripheral portions 462 of the keyassembly, which are coupled to the protruding portions (bosses) 466, maydeflect away from the interior surface of the housing 414. In somecases, the protruding portions (bosses) 466 may protrude from the holes422 when the downward force 490 is applied to the cap 456. When thedownward force 490 is removed from the cap 456 (e.g., when a user nolonger applies force to the cap), the key assembly 451 may provide anupward biasing force to return the cap 456 to its original position.More generally, a biometric input component may not include a keyassembly but may include another type of mechanism to allow the cap tobe depressed, such as a scissor mechanism or a butterfly mechanism.

FIG. 5A shows a top view of a cap 556 for a biometric input component,such as a biometric button or key. The cap 556 includes a ceramic cover580. The cap 556 of the biometric input component may be configured tohave a visual and/or tactile property similar to that of an adjacentkeycap of the electronic device. The cap 556 may be an example of thecap 156 or the cap of any other biometric input key described herein.Ceramic covers are described in more detail with respect to FIGS. 6A-8and the description provided with respect to FIGS. 6A-8 is generallyapplicable herein. As shown in more detail in the cross-section view ofFIGS. 6A-8 , the cap 556 may also include one or more coatings appliedto a front surface of the ceramic cover and one or more coatings appliedto a rear surface of the ceramic cover. The description of thesecoatings provided with respect to FIGS. 6A-8 is generally applicableherein and, for brevity, is not repeated here.

In the example, of FIG. 5A, the front surface 572 of the cap 556generally has the shape of a square with rounded corners. However, itshould be understood that the example of FIG. 5A is not limiting and thefront surface of the cap 556 may have another shape, such as a rectangle(with or without rounded corners), a circle, an ellipse, an oblong, apolygon (with or without rounded corners), and the like. In some cases,the shape of a front surface of the cap 556 may be similar to that of anadjacent key of the keyboard.

FIG. 5B shows an example of a side view of the cap 556 of FIG. 5A. Asshown in FIG. 5B, the cap 556 has a thickness T and a lateral dimensionL (e.g., a width or a length of the square shape of FIG. 5A). Asexamples, the thickness T may be from 100 microns to 750 microns, from100 microns to 400 microns, or from 200 microns to 500 microns. Asexamples, the lateral dimension may be from about 0.5 cm to about 5 cmor from about 0.5 cm to 2 cm. The cap 556 of FIG. 5B includes a frontsurface 572, a side surface 574, and a curved surface 576 which extendsbetween the front surface 572 and the side surface 574. In some cases, aside surface of a cap, such as side surface 574, may simply be referredto herein as a side of a cap. In some embodiments, the rounded or curvedsurface 576 may be referred to as a rounded edge or corner. The roundedsurface 576 may be characterized by a radius of curvature as explainedin further detail with respect to the detail view of FIG. 6A and thedescription of the rounded surface provided with respect to FIG. 6A isgenerally applicable herein.

FIG. 6A shows a partial cross-section view of a cap 656 for a biometricinput component, such as a biometric button or key. For example, thecross-section may be along E-E in area F-F of FIG. 5A. The cap 656includes a ceramic cover 680 and may be configured to have a visualand/or tactile property similar to that of an adjacent keycap of theelectronic device. As schematically shown in FIG. 6A, a front surface682 and a curved surface 686 of the ceramic cover 680 are textured. Acover provided over the biometric input component, such as ceramic cover680, may also be referred to generally herein as a cover member, a capmember, or simply as a member. The cap 656 may be an example of the cap156 or the cap of any other biometric input key described herein.

The curved surface 686 of the ceramic cover 680 may define a radius ofcurvature R. In some embodiments, the radius of curvature is from about0.05 mm to about 0.3 mm, from about 0.05 mm to about 0.2 mm, or fromabout 0.1 mm to about 0.2 mm. In some cases, the mean radius ofcurvature is from about 0.05 mm to about 0.3 mm, from about 0.05 mm toabout 0.2 mm, from about 0.1 mm to about 0.25 mm, or from about 0.1 mmto about 0.2 mm. The radius of curvature R may vary at least in part dueto the texture of the curved surface 686. In some cases, the variationof the radius of curvature along the curved surface is controlled towithin 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% of a target radius ofcurvature or a mean radius of curvature. For example, a tolerance of theradius of curvature of the curved edge may be from 0% to 5%, 0% to 10%,0% to 15%, 0% to 20%, 0% to 25%, 0% to 30%, 0% to 35%, or 0% to 40% of atarget radius of curvature. Control of the radius of curvature along thecurved surface can help provide a uniform visual appearance to the cap656. The curved surface 686 extends between the front surface 682 andthe side surface 684.

The ceramic cover 680 comprises a ceramic material and may substantiallyor essentially consist of the ceramic material. The ceramic material maybe a dielectric and electrically insulating material. The ceramicmaterial typically transmits visible light (is light transmissive) andin some case may have a transmittance of at least 75%, 80%, or 85% inthe visible spectrum. The ceramic material may also be transparent orsubstantially transparent as polished, as textured, or both. The ceramicmaterial is typically crystalline and may substantially or essentiallyconsist of a single crystal. In some cases, the ceramic material maysubstantially or essentially consist of single crystal alumina, e.g.,single crystal alpha alumina or sapphire. The description of crystalorientations of single crystal sapphire provided with respect to FIG. 9are generally applicable herein, and, for brevity, are not repeatedhere. Sapphire may appear substantially transparent and colorless or mayinclude a dopant to provide a desired color cast or tint (e.g., red,orange, yellow, green, blue, violet, or purple).

As shown in FIG. 6A, a rear coating 692 is disposed over a rear surface688 of the ceramic cover 680. The rear coating 692 may cover the rearsurface 688. In some embodiments, the rear coating 692 is configured togive one or more visual properties to the cap 656 and may be referred toas a decorative or cosmetic coating. The rear coating 692 may beconfigured to absorb one or more wavelengths of visible light, therebycontributing to the perceived color of the cap 656. For example, therear coating 692 may absorb over a broad band of the visible spectrumand may have a dark appearance.

In some cases, the rear coating 692 may be optically dense. For example,the optical density of the rear coating 692 may be described by OD=log₁₀(initial intensity/transmitted intensity) and may be greater than orequal to 1, greater than or equal to 2, or greater than or equal to 3,from about 2 to about 5, from about 3 to about 5, or from about 3 toabout 4. In some cases, the thickness of the rear coating 692 may befrom 0.5 microns to 2.5 microns, from 0.5 microns to 2 microns, from 1micron to 2 microns, or from 0.5 microns to 1.5 microns. The descriptionprovided with respect to FIGS. 6A and 6B is generally applicable herein.

The rear coating 692 may be a multilayer coating comprising multiplelayers, as shown in the detail view of FIG. 6B. For example, the rearcoating may be an inorganic multilayer coating. In some cases, theinorganic multilayer coating comprises multiple dielectric layers andmultiple metal layers and may be referred to as a metal-dielectriccoating. Additional description of the rear coating is provided withrespect to FIG. 6B and, for brevity, is not repeated here.

The cap 656 also includes a front coating 694 disposed over a frontsurface 682 of the ceramic cover 680. The front coating 694 may coverthe front surface 682. In some cases, the front coating 694 comprises orconsists of an anti-reflection coating. For example, the anti-reflectioncoating may be configured to produce destructive interference of lightreflected from the coating and light reflected from the ceramic cover680 and may thereby provide an anti-reflection effect.

An anti-reflection coating included in front coating 694 may comprise aninorganic dielectric material. For example, the front coating 694 maycomprise an oxide (e.g., a metal oxide such as aluminum oxide or asilicon oxide) or a nitride (e.g., a metal or a silicon nitride). Thefront coating 694 may be a multilayer coating, such as an inorganicmultilayer coating. For example, a multilayer anti-reflection coatingmay have two, three, four, five, six, or more layers. In someembodiments, the anti-reflection coating includes a first layercomprising a first inorganic dielectric material and a second layercomprising a second inorganic dielectric material. The first inorganicdielectric material may have an index of refraction less than an indexof refraction of the ceramic cover and the second inorganic dielectricmaterial may have an index of refraction greater than the index ofrefraction of the ceramic cover. In some cases, the antireflection layermay further include a third inorganic dielectric material different fromthe first and the second inorganic dielectric materials. For example,the third inorganic dielectric material may have an index of refractionsubstantially similar to that of the ceramic cover. The additionaldescription of dielectric materials provided with respect to FIG. 9 isgenerally applicable herein and, for brevity, is not repeated here.

In some cases, the anti-reflection coating may have a thickness fromabout 50 nm to about 200 nm, from about 75 nm to about 150 nm, fromabout 50 nm to about 125 nm, or from about 25 nm to about 100 nm. Eachlayer of the anti-reflection coating may be thin, such as from 1 nm to200 nm, 5 nm to 150 nm, or from 10 nm to 75 nm. The anti-reflectioncoating included in the front coating 694 may have a thickness less thanan arithmetic mean height (or root mean square height) of surfacefeatures defining a texture of the ceramic cover 680. For example, thethickness of the anti-reflection coating may be from about 0.1 to about0.5 times or from about 0.2 to about 0.5 times the arithmetic meanheight (or root mean square height) of the surface features.

In some cases, the front coating 694 further includes an anti-smudgecoating. The detail view of FIG. 7B shows an example of an anti-smudgecoating provided over an anti-reflection coating. In some cases, ananti-smudge coating may comprise a fluorinated material, such as afluorinated oligomer or polymer, to impart oleophobic and/or hydrophobicproperties. For example, the contact angle of an oil on the coating maybe greater than or equal to about 65 degrees or about 70 degrees. As anadditional example, the contact angle of water on the coating may begreater than or equal to 90 degrees. The fluorinated material maycomprise a linear (non-branched) fluorinated molecule such as a linearfluorinated oligomer or a linear fluorinated polymer.

As shown in FIG. 6A, the front surface 682 of the ceramic cover 680comprises a plurality of surface features 683 which define a firsttexture of the ceramic cover. Similarly, the curved surface 686 of theceramic cover 680 comprises a plurality of surface features 687 whichdefine a second texture of the ceramic cover. In some embodiments, thesurface features 683 and 687 are not individually visually perceptible.FIGS. 7A-7B show examples of detail views of surface features on thefront surface 682 and FIG. 8 shows an example detail view of surfacefeatures on the curved surface 686 of the ceramic cover 680. Thedescription of surface features provided with respect to FIGS. 7A-8 isgenerally applicable herein and, for brevity, is not repeated here

The surface features 683 and 687 may be configured to provide particularoptical properties to one or more surfaces of the ceramic cover 680 andto contribute to one or more optical properties of the cap 656. Forexample, the surface features 683 and 687 may be configured to provideparticular values of such optical properties such as gloss to theceramic cover 680. In some cases, the texture defined by a surface ofthe ceramic cover 680 may cause the ceramic cover 680 to appeartranslucent, rather than transparent. A translucent surface of theceramic cover can more closely resemble the surface of the keycap ofanother key. In addition, the front coating 694 and/or the rear coating692, in combination with the textured surfaces of the ceramic cover 680,may be configured to provide particular values of such opticalproperties such as gloss, reflective haze, reflectance, color, andcombinations thereof to the cap 656.

In some cases, the surface features 683 and 687 may be configured todiffusely reflect incident light. The surface features 683 and 687 maydefine any of a range of shapes or configurations which can diffuse orscatter incident light. For example, the surface features 683 and/or 687may define protrusions and/or recesses. The surface features 683 and/or687 may also define sets of hills and valleys. The first texture definedby the surface features 683 and the second texture defined by thesurface features 687 may also be configured to diffusely reflectincident light.

A texture of a surface of the ceramic cover 680, such as the firsttexture of the front surface 682 and/or the second texture of the curvedsurface 686, may be configured to provide a specified gloss level to thesurface. In some embodiments, a textured surface of the ceramic cover680 may have a gloss value of from about 5 to about 20 or from about 10to about 20 (in the absence of a rear coating and in the absence of afront coating on the cover 680). Further, the gloss of a textured frontsurface 672 of the cap 656 (in the presence of a rear coating and afront coating as described herein) may be less than that of the texturedsurface of the ceramic cover 680. In some cases, the gloss of a texturedfront surface 672 of the cap 656 may be from about 1 to about 10 or fromabout 2 to about 8. In some cases, the gloss may be measured usingcommercially available equipment and according to ASTM or ISO standardtest methods. The gloss measurement may be referenced to a particularangle, such as 85 degrees, 60 degrees, or 45 degrees. The anglemeasurement may refer to the angle between the incident light andperpendicular to the surface.

A textured surface of the ceramic cover 680, such as the front surface682 and/or the curved surface 686, may be configured to provide aspecified level of reflective haze or extent of diffuse reflection (alsoreferred to as the diffuse reflectance) to the corresponding portion ofthe ceramic cover. In some cases, the reflective haze of a texturedsurface, such as the front surface 682 of the ceramic cover or the frontsurface 672 of the cap 656, may be measured using commercially availableequipment and according to ASTM or ISO standard test methods. Themeasurement may use a CIE standard illuminant A or a standard illuminantC. The reflective haze of the front surface 672 of the cap 656 (e.g.,with a rear coating and a front coating) may be from about 30 to about70, from about 35 to about 60, or from about 35 to about 55. As anon-limiting example, the reflective haze or extent of diffusereflection may be measured using a SMS-1000 available from DM&S(Display-Messtechnik & Systeme). A transmissive haze may also bemeasured for a textured surface of the ceramic cover 680 (prior toapplication of an opaque rear coating).

An anti-reflection property of the surface of the cap 656, such as thefront surface 672, may be determined from its reflectance spectrum overa specified range of wavelengths, such as the visible spectrum of light(e.g., from about 380 nm to about 780 nm), also referred to as thevisible spectrum. A reflectance of a surface of the cap 656, such as thefront surface 672 of the cap 656, may be less than about 15%, fromgreater than or equal to 5% to less than about 15%, less than about 12%,from about 1% to about 15%, or from about 5% to about 12% across thevisible spectrum. In comparison, the reflectance of a polished ceramiccover may be greater than that of the surface of the cap, such at least25%, at least 50%, at least 100%, at least 200%, from 25% to 500%, orfrom 50% to 500% greater than that of the cap. The reflectance may bemeasured using commercially available equipment.

In addition, coordinates in CIEL*a*b* (CIELAB) color space may be usedto characterize a color of a surface of the cap 656, such as the frontsurface 672. In CIEL*a*b* (CIELAB) color space, L* representsbrightness, a* the position between red/magenta and green, and b* theposition between yellow and blue. A broadband or semi-broadbandilluminant may be used to determine the color of the surface. Forexample, a CIE illuminant or other reference illuminant may be used. Thecolor of the surface may be determined from the light reflected at aparticular viewing angle (e.g., a viewing angle approximately alignedwith or at an angle to the direction of incident light).

In some cases the cap 656 (or the cover assembly) has first colordescribed by a first L* value; at least one keycap of the array of keyshas a second color described by a second L* value; and a differencebetween the first L* value and the second L* value is less than 20, lessthan 10, less than or equal to 5, or less than or equal to 3, less thanor equal to 2, or less than or equal to 1. Similarly, the difference ina*, b*, and/or Delta E may be less than 20, less than 10, less than orequal to 5, less than or equal to 3, less than or equal to 2, or lessthan or equal to 1. For example, Delta E may be the square root of thesum of the squares of the differences in L*, a*, and b*. Each of thedifference in L*, a*, and b* may be within one of the ranges givenabove. In some cases, the difference in a* may be less than thedifference in L* and b*.

A textured surface of the ceramic cover 680, such as the front surface682 and/or the curved surface 686, may also be configured to provide aspecified level of cleanability. For example, the texture may also beconfigured so that a size of any recessed surface feature issufficiently large to facilitate cleaning.

Surface texture parameters include areal surface texture parameters suchas amplitude parameters, spatial parameters, and hybrid parameters.Surface filtering may be used to exclude surface noise and/or surfacewaviness before determining the surface texture parameters. In addition,a segmentation technique may be used to determine feature parameterssuch as the maximum diameter, the minimum diameter, the area, and theperimeter. These parameters may be calculated on the basis of thefeature shape as projected onto the reference surface (e.g., a referenceplane). Mean values may be determined for a given class of surfacefeatures (e.g., hills or valleys). Surface texture parameters andmethods for determining these parameters (including filtering andsegmentation) are described in more detail in International Organizationfor Standardization (ISO) standard 25178 (Geometric ProductSpecifications (GPS)—Surface texture: Areal). These surface textureparameters may be measured using commercially available equipment.

For example, the surface features (e.g., 683 and/or 687) of one or moresurfaces of the ceramic cover 680 may be characterized, in part, by theheights of the surface features. The height may be measured with respectto a reference surface, such as the arithmetic mean of the surface(schematically shown by line 730 in FIG. 7A). The heights of the surfacefeatures (e.g., 683 and/or 687) may not be uniform, so that the surfacefeatures have a distribution of heights. The magnitude of the heights ofthe surface features (683, 687) may fall in the range from zero to about1 micron. The surface features 683, 687 may be characterized by the rootmean square height Sq or the arithmetic mean height Sa of the surface(also referred to as the arithmetical mean height). The arithmetic meanheight of the surface features 683, 687 may be greater than about 100 nmand less than or equal to about 700 nm, from about 150 nm to about 600nm, from about 200 nm to about 500 nm, or from about 300 nm to about 700nm.

FIG. 6B shows a detail view of the cap of FIG. 6A. As shown in FIG. 6B,the rear coating 692 is disposed on a rear surface 688 of the ceramiccover 680. In the example of FIG. 6B, the rear coating 692 comprisesmultiple layers. For simplicity of illustration, FIG. 6B schematicallyindicates a first set of layers near the rear surface 688 of the cover680 (e.g., layers 692 a, 692 b, 692 c), a second set of layers near theinterior surface of the coating (e.g., layers 692 n and 692 n+1), and agap between the first and the second sets of layers. However, moregenerally, the rear coating 692 may have a lesser or greater number ofcoating layers than shown in FIG. 6B. For example, the rear coating 692may include from 1 layer to 100 layers, from 10 layers to 75 layers, orfrom 20 layers to 50 layers. Each coating layer may be thin, such asfrom 1 nm to 200 nm, from 1 nm to 150 nm, from 1 nm to 100 nm, from 1 nmto 10 nm, from 1 nm to 5 nm, from 5 nm to 50 nm, from 10 nm to 75 nm, orfrom 50 nm to 150 nm.

In some embodiments, at least some of the coating layers may vary incomposition. For example, the rear coating 692 may include one or morelayers of a first material and one or more layers of a second materialdifferent than the first material. In some cases, the first material isan inorganic dielectric material and the second material is a metal. Thedielectric material may be an oxide material (e.g., a metal oxide or asilicon oxide) or a nitride material (e.g., a metal nitride or a siliconnitride). The metal of the metal layer may comprise or consistessentially of aluminum, chromium, cobalt, gold, molybdenum, nickel,silver, tin, and the like and alloys and combinations thereof. Thedielectric layer(s) may be thicker than the metal layer(s). Further, therear coating 692 may include one or more layers having a thirdcomposition different than the first composition and the secondcomposition. In some cases, at least some of the metal layers alternatewith dielectric layers in the rear coating 692. For example, each metallayer may be “sandwiched” between dielectric layers (e.g., betweenlayers of a silicon oxide, a silicon nitride, or combinations thereof).

FIG. 7A shows a detail cross-section view of the cap of FIG. 6A. The cap756 includes a ceramic cover 780 and may be configured to have a visualand/or tactile property similar to that of an adjacent keycap of theelectronic device. FIG. 7A may be a detail view of region H-H of FIG.6A. The cap 756 may be an example of the cap 156 or of any other capdescribed herein. As shown in FIG. 7A, the front surface 782 of theceramic cover 780 defines a set of surface features 783. A front coating794 is disposed over the set of surface features 783.

As shown in FIG. 7A, the front coating 794 may be thin relative to thesurface features 783 of the ceramic cover 780. The front coating 794 mayinclude an anti-reflection coating. The description of anti-reflectioncoatings provided with respect to FIG. 6A is generally applicable hereinand, for brevity, will not be repeated here. In some cases, ananti-reflection coating included in the front coating 794 may have athickness from 50 nm to about 200 nm, from about 75 nm to about 150 nm,from about 50 nm to about 125 nm, or from about 25 nm to about 100 nm.In addition, the anti-reflection coating may have a thickness that issubstantially uniform. The ceramic cover 780 may be an example of theceramic cover 680 or any other ceramic covers described herein.Similarly, the front coating 794 may be an example of the front coating694 or any front coatings described herein. Details of these ceramiccovers and front coatings are applicable to the ceramic cover 780 andfront coating 794 and, for brevity, will not be repeated here.

As shown in FIG. 7A, the surface features 783 may define one or morerecesses, such as the surface feature 734. A recess may define a minimumpoint. The surface features 783 may also define one or more protrusions,such as the surface feature 732. A protrusion may define a maximumpoint. As schematically shown in FIG. 7A, the surface features 783 maydefine a set of minimum points as well as a set of maximum points. Theset of maximum points may also be referred to as a set of peaks. Thesurface features 783 may define a set of recesses, each recess beingpositioned between adjacent peaks of the set of peaks. The shapes of thepeaks and the valleys are not limited to those schematically shown inFIG. 7A.

In some embodiments, the surface features 783 define a set of hills andvalleys. The hills and valleys may be defined using areal textureanalysis techniques as previously described with respect to FIG. 6A. Thesurface feature 732 may generally correspond to a hill feature and thesurface feature 734 may generally correspond to a valley feature. Insome embodiments, a set of hills and valleys has a substantially uniformspacing between hill features, valley features, or a combinationthereof. In additional embodiments, a set of valleys may have anon-uniform or an irregular spacing between hill features and/or valleyfeatures.

The heights of the surface features 783 may be measured with respect toa reference surface 730. For example, the heights of the hills may bedetermined from the maximum points and the heights of the valleys may bedetermined from the minimum points. In some cases, the reference surfaceis the arithmetical mean of the surface.

The example of the surface features 783 provided in the cross-sectionalview of FIG. 7A is not limiting and in general the surface features 783may define any of a range of shapes or configurations. The surfacefeatures 783 may have a variety of shapes, such as rounded or angularfeatures. As examples, the surface features 783 may define a circular,oval, polygonal, rectangular, or irregular surface contour. Furthermore,the surface features 783 may define protrusions, recesses, or acombination thereof and may have any suitable shape and may bepyramidal, conical, cylindrical, arched, have a curved upper surface ora frustum of a shape such as a cone, and so on.

FIG. 7B shows a detail cross-section view of the cap of FIG. 7A. FIG. 7Bmay be a detail view of region J-J of FIG. 7A. As shown in FIG. 7B, thefront surface 782 of the ceramic cover 780 defines surface features 732and 734. The front coating 794 includes an anti-reflection coating 795disposed over the surface features 732 and 734. An anti-smudge coating796 is disposed over the anti-reflection coating 795.

As shown in FIG. 7B, the anti-smudge coating 796 may be thin relative tothe thickness of the anti-reflection coating 795 and the surfacefeatures 732,734. In embodiments, the anti-smudge coating 796 comprisesa layer of fluorinated material which is from about 5 nm to about 20 nmthick or from about 10 nm to about 50 nm thick. In some cases, the layerof the fluorinated material is bonded directly to the anti-reflectionlayer. The description of anti-smudge and anti-reflection coatingsprovided with respect to FIG. 6A is generally applicable herein and, forbrevity, will not be repeated here.

FIG. 8 shows another detail cross-section view of the cap of FIG. 6A.The cap 856 includes a ceramic cover 880 and may be configured to have avisual and/or tactile property similar to that of an adjacent keycap ofthe electronic device. FIG. 8 may be a detail view of region I-I of FIG.6A. The cap 856 may be an example of the cap 156 or of any other capdescribed herein. As shown in FIG. 8 , the curved surface 886 of theceramic cover 880 defines a set of surface features 887. A front coating894 is disposed over the set of surface features 887.

In the examples of FIGS. 8 and 7A, the surface features 887 of thecurved surface 886 are not identical to the surface features 783 of thefront surface 782. For example, the surface features 887 of the curvedsurface 886 may differ in shape and/or one or more roughness parametersfrom the surface features 783 of the front surface 782. In some cases,differences between the surface features 887 of the curved surface 886and the surface features 783 of the front surface 782 may result fromdifferences in the methods used to form the texture on the curvedsurface 886 and the front surface 782, as explained in more detail withrespect to FIG. 9 .

The ceramic cover 880 may be an example of the ceramic cover 680 or anyother ceramic covers described herein. Similarly, the front coating 894may be an example of the front coating 694 or any front coatingsdescribed herein. Details of these ceramic covers and front coatings areapplicable to the ceramic cover 880 and front coating 894 and, forbrevity, will not be repeated here.

FIG. 9 shows a flow chart of an example process 900 for making atextured cap for a biometric input component. The biometric inputcomponent may be a biometric button or key. The textured cap includes atextured ceramic cover and may be configured to have a visual and/ortactile property similar to that of an adjacent keycap of the electronicdevice. The textured cap may include the textured ceramic cover, one ormore coatings applied to a rear surface of the ceramic cover, and one ormore coatings applied to a textured front surface of the ceramic cover.Although the example of FIG. 9 describes texturing of a sapphire cover,the operations of process 900 may also apply to texturing of coversformed from ceramic materials other than sapphire.

As shown in FIG. 9 , the process 900 includes an operation 902 offorming a texture on a sapphire wafer. The sapphire wafer may have alarger lateral dimension than an individual sapphire cover to be formed.Typically, multiple sapphire covers are formed from a single sapphirewafer. Prior to the operation 902, the sapphire wafer may have a surfaceroughness corresponding to that of a polished surface, such as a Sa ofless than about lnm or less than about 5 nm. The front and/or rear faceof the sapphire wafer may have a particular crystal orientation, such aC-plane orientation, an A-plane orientation, an R-plane orientation, anM-plane orientation, or an orientation that is at a specified angle toone of these orientations. In some cases, the front face and the rearface of the sapphire wafer may have a common crystal orientation. Thewafer may be thin, such as from 100 microns to 750 microns, from 100microns to 400 microns, or from 200 microns to 500 microns. Thedescription of sapphire materials provided with respect to FIG. 6A isgenerally applicable herein and, for brevity, is not repeated here.

In some cases, the texture may be formed on only one of the main facesof the sapphire wafer. For example, the texture may be formed on themain face of the sapphire wafer which will become the front surface ofthe sapphire cover; this face is referred to herein as the front face ofthe sapphire wafer. The texture may be formed across a substantialentirety of the front surface of the sapphire wafer.

In some embodiments, the operation 902 may include applying an abrasivetreatment to the sapphire wafer, also referred to herein as gritblasting. The abrasive treatment may comprise directing a stream ofabrasive particles at the sapphire wafer. When the texture is to beformed on the front face, but not the rear face, of the sapphire wafer,a mask may be used to shield the other rear face (and optionally theside surfaces) of the wafer. The abrasive treatment may be a wet or adry grit blasting process. The abrasive particles may comprise ceramicparticles having an average size ranging from about 10 microns to about75 microns. The ceramic particles may have a hardness greater than thatof alumina (e.g., diamond particles or silicon carbide particles).Following the abrasive treatment, small pits, small fissures, or othersuch features may be formed along an exterior surface of the sapphirewafer. Typically the sapphire wafer is washed following the abrasivetreatment. The sapphire wafer may also be annealed following theabrasive treatment. The annealing temperature may be less than a meltingtemperature of the sapphire wafer, such as from about 1000° C. to about1500° C. The sapphire wafer may be annealed under oxidizing conditions,such as in an air atmosphere or an atmosphere comprising a mixture ofoxygen with a gas such as nitrogen, argon, and the like, or under inertconditions.

The process 900 further includes an operation 904 of forming anadditional texture on the sapphire wafer. In some embodiments, operation904 forms the additional texture by a method other than abrasivetreatment. For example, operation 904 may include laser-texturing thefront face of the sapphire wafer. Operation 904 may include directing asequence of laser pulses onto the front surface of the sapphire wafer.The laser pulses may be formed by a first laser.

The first laser may be operated at a first set of laser conditions. Forexample, the first laser may produce a wavelength in the infrared range(e.g., having a wavelength from about 1 μm to about 5 μm). The firstlaser may produce pulses having a duration in the picosecond range, suchas from about 1 ps to about 50 ps. The average power of the first lasermay be from about 20 W to about 70 W. The repetition rate of the firstlaser may be from about 100 kHz to about 750 kHz. The scan speed may bevaried as desired and, in some embodiments, may be from about 250 mm/sto about 1250 mm/s. The spot size may be from about 10 microns to about30 microns.

In some cases, each pulse of the laser beam may transfer energy to thesapphire wafer, including an exposure area on the surface of thesapphire wafer and the region of the sapphire wafer within the focalvolume of the laser beam. In order to etch the surface of the sapphirewafer, a sufficient amount of energy is transferred to the sapphirewafer along the exposure area to cause ablation of the sapphire wafer.The sapphire wafer may have an ablation threshold, which may bedescribed in terms of the fluence (J/cm²) of the laser.

Ablation of sapphire can form an ablation feature along the surface ofthe sapphire wafer. An ablation feature formed along a relatively flatsurface of a sapphire wafer may include a depression (or crater) in thesurface of the ceramic cover. As the surface of the sapphire waferbecomes more rough (e.g., as a result of a previous ablation of thesurface), the shape of the ablation features may become less regular. Insome cases, operation 904 may also form the curved surface (or roundededge) of the sapphire cover. In other embodiments, a separate operation,such as a separate laser-ablation operation, may be used to form thecurved surface of the sapphire cover.

The process 900 further includes an operation of 906 of singulating(also, separating) the sapphire wafer into parts to form one or morecovers. The operation 906 may also form one or more remainder parts ofthe sapphire wafer (e.g., along the sides of the wafer). The operation906 may include cutting or breaking the sapphire wafer in one or morespecified regions of the sapphire wafer (e.g., a separation regionbetween two parts). Although FIG. 9 illustrates the operation 906 asfollowing the operation 904, this example is not limiting and in somecases the operation 904 may follow the operation 906. In addition, insome cases, the operation 906 may also form the curved surface (orrounded edge) of the sapphire cover.

In some embodiments, the operation 906 may include one or more lasertreatment steps. The operation 906 may include an operation of directinga beam from a second laser onto the separation region of the sapphirewafer. As examples, the second laser may be configured to ablatesapphire material in the separation region (e.g., ablation cutting), ormay be configured to create filaments/voids in the separation regionthrough non-linear optical effects. In the latter case, the parts may beseparated mechanically, or by application of thermal energy, such asfrom a third laser.

The second laser may be operated at a second set of laser conditions.For example, the second laser may produce a wavelength in the infraredrange (e.g., having a wavelength from about 1 μm to about 5 μm). Thesecond laser may produce pulses having a duration in the picosecondrange, such as from about 1 ps to about 50 ps. The average power of thesecond laser may be from about 5 W to about 20 W. The repetition rate ofthe first laser may be from about 10 kHz to about 75 kHz. The scan speedmay be varied as desired and, in some embodiments, may be from about 25mm/s to about 125 mm/s. The spot size may be from about 2 microns toabout 10 microns. The third laser may be operated at a third set oflaser conditions. For example, the third laser may be a carbon dioxidelaser producing a wavelength in the infrared range (e.g., having awavelength from about 9 μm to about 11 μm). In some embodiments, thethird laser operates in continuous mode rather than pulsed mode.

The process 900 further includes an operation 908 of applying a coatingto a rear surface of the cover(s). This coating may also be referred toas a rear coating. In some embodiments, the rear coating is configuredto give one or more visual properties to the textured sapphire cover andmay be referred to as a decorative or cosmetic coating. As describedwith respect to FIGS. 6A-6B, the rear coating may be configured toabsorb one or more wavelengths of visible light, thereby contributing tothe perceived color of the textured sapphire cover. The description ofthe rear coating provided with respect to FIGS. 6A-6B is generallyapplicable herein and, for brevity, is not repeated here.

In embodiments, the coating may be applied to the rear surface of thesapphire cover using a physical vapor deposition (PVD) technique.Physical vapor deposition techniques include, but are not limited to,sputtering and evaporation techniques. Physical vapor deposition can beused to deposit layers of different compositions. The layers may besubstantially dense (e.g., substantially non-porous). In some cases, thethickness of the rear coating may be from 0.5 microns to 2.5 microns,from 0.5 microns to 2 microns, or from 1 micron to 2 microns.

In some cases, the rear coating may comprise multiple layers as shown inthe example of FIG. 6B. For example, the rear coating may include from 1layer to 100 layers, from 10 layers to 75 layers, or from 20 layers to50 layers. Each coating layer may be thin, such as from 1 nm to 200 nm,from 1 nm to 150 nm, from 1 nm to 100 nm, from 1 nm to 10 nm, from 1 nmto 5 nm, from 5 nm to 50 nm, from 10 nm to 75 nm, or from 50 nm to 150nm.

In some embodiments, at least some of the coating layers of the rearcoating may vary in composition. For example, the rear coating mayinclude one or more layers of a first material and one or more layers ofa second material different than the first material. In some cases, thefirst material is a inorganic dielectric material and the secondmaterial is a metal. The dielectric material may be an oxide material(e.g., a metal oxide or a silicon oxide) or a nitride material (e.g. ametal nitride or a silicon nitride). The metal of the metal layer maycomprise or consist essentially of aluminum, chromium, cobalt, gold,molybdenum, nickel, silver, tin, and the like and alloys andcombinations thereof. The dielectric layer(s) may be thicker than themetal layer(s). Further, the rear coating may include one or more layershaving a third composition different than the first composition and thesecond composition. For example, the rear coating may include one ormore layers of a third material which is a dielectric material differentfrom the first material. The number of layers of the third material maybe less than the number of layers of the first material and the secondmaterial. In some cases, at least some of the layers of the dielectricmaterial(s) may alternate with the layers of the metal material aspreviously described with respect to FIG. 6B. Additional description ofdielectric compositions is provided below with respect to operation 910and, for brevity, is not repeated here.

The process 900 further includes an operation 910 of applying a coatingto a front surface of the cover(s). For example, operation 910 mayinclude disposing an anti-reflection coating over the front surface ofthe cover(s). In some cases, an adhesion layer may be applied to thefront surface of the cover(s) before the anti-reflection coating isdisposed over the front surface. Further, operation 910 typicallyincludes disposing an anti-smudge coating over the front surface of thecover(s). For example, the anti-smudge coating may be applied over theanti-reflection coating. Although FIG. 9 illustrates the operation 910as following the operation 908, this example is not limiting and in somecases the operation 908 may follow the operation 910 or may beintermediate between two steps of operation 910 (e.g., intermediatebetween a step of applying an anti-reflection coating and a step ofapplying an anti-smudge coating).

In some embodiments, an anti-reflection coating and/or an adhesion layermay be applied to the front surface of the sapphire cover using aphysical vapor deposition (PVD) technique. Physical vapor depositiontechniques include, but are not limited to, sputtering and evaporationtechniques. Physical vapor deposition can be used to deposit layers ofdifferent compositions.

The anti-reflection coating may comprise an inorganic dielectricmaterial. For example, the anti-reflection coating may comprise an oxide(e.g., a metal or a silicon oxide) or a nitride (e.g., a metal or asilicon nitride). The anti-reflection coating may be a multilayercoating. For example, a multilayer anti-reflection coating may have two,three, four, five, six, or more layers. In some embodiments, theanti-reflection coating includes a first layer comprising a firstinorganic dielectric material and a second layer comprising a secondinorganic dielectric material. A first inorganic dielectric material mayhave an index of refraction less than an index of refraction of theceramic cover and a second inorganic dielectric material may have anindex of refraction greater than the index of refraction of the ceramiccover. In some cases, the antireflection layer may further include athird inorganic dielectric material different from the first and thesecond inorganic dielectric materials.

The anti-reflection coating may have a thickness from about 50 nm toabout 200 nm, from about 75 nm to about 150 nm, from about 50 nm toabout 125 nm, or from about 25 nm to about 100 nm. Each coating layermay be thin, such as from 1 nm to 200 nm, from 5 nm to 150 nm, from 5 nmto 100 nm, from 5 nm to 75 nm, or from 5 nm to 50 nm. The layers may besubstantially dense (e.g., substantially non-porous).

Suitable oxides include, but are not limited to, a silicon oxide (e.g.,SiO_(x) where x may be about 2), aluminum oxide (Al₂O₃), niobium oxide(e.g., Nb₂O₅), titanium oxide (e.g., TiO₂), tantalum oxide (e.g.,Ta₂O₅), zirconium oxide (e.g., ZrO₂), magnesium oxide (e.g., MgO), andthe like. Suitable nitrides include, but are not limited to, siliconnitride (SiN_(x) where x may be greater than zero and less than or equalto about 1.3, Si_(x)N_(y) where x may be about 3 and y may be about 4),silicon oxynitride (e.g., SiO_(x)N_(y) which may vary in compositionbetween SiO₂ and Si₃N₄) and the like. The layers of inorganic dielectricmaterial may be substantially transparent to visible light. Thedescription provided herein with respect to silicon and metal oxides,nitrides, and oxynitrides is generally applicable to the dielectriclayers described herein, including those included in the coatingprovided over the rear surface of the ceramic cover.

In some embodiments, an adhesion layer is applied to the front surfaceof the sapphire cover to enhance adhesion between the sapphire cover andthe anti-reflection coating. The adhesion layer may be thin, such asfrom about 1 nm to about 25 nm, from about 5 nm to about 15 nm, or fromabout 5 nm to about 10 nm. The adhesion layer may be a metal oxide layerand for example may comprise alumina (Al₂O₃), silica (SiO₂), or a mixedoxide such as (AlO_(x)—SiO_(y)).

Typically, an anti-smudge coating is applied over the anti-reflectionlayer. As previously described with respect to FIG. 6B, the anti-smudgecoating may have hydrophobic and/or oleophobic properties. Theanti-smudge coating may also comprise a fluorinated material. A layer ofthe fluorinated material may be formed through a wet chemistry method orby a vapor deposition method.

FIG. 10 shows a block diagram of a sample electronic device that canincorporate a biometric input component having a textured cap. Thetextured cap includes a textured ceramic cover and may be configured tohave a visual and/or tactile property similar to that of an adjacentkeycap of the electronic device. The biometric input component may be abiometric button or key. The schematic representation depicted in FIG.10 may correspond to components of the devices depicted in FIGS. 1A-9 asdescribed above. However, FIG. 10 may also more generally representother types of electronic devices with cap assemblies as describedherein.

In embodiments, an electronic device 1000 may include sensors 1020 toprovide information regarding configuration and/or orientation of theelectronic device in order to control the output of the display. Forexample, a portion of the display 1008 may be turned off, disabled, orput in a low energy state when all or part of the viewable area of thedisplay 1008 is blocked or substantially obscured. As another example,the display 1008 may be adapted to rotate the display of graphicaloutput based on changes in orientation of the device 1000 (e.g., 100degrees or 180 degrees) in response to the device 1000 being rotated.

The electronic device 1000 also includes a processor 1006 operablyconnected with a computer-readable memory 1002. The processor 1006 maybe operatively connected to the memory 1002 component via an electronicbus or bridge. The processor 1006 may be implemented as one or morecomputer processors or microcontrollers configured to perform operationsin response to computer-readable instructions. The processor 1006 mayinclude a central processing unit (CPU) of the device 1000.Additionally, and/or alternatively, the processor 1006 may include otherelectronic circuitry within the device 1000 including applicationspecific integrated chips (ASIC) and other microcontroller devices. Theprocessor 1006 may be configured to perform the functionality describedin the examples above.

The memory 1002 may include a variety of types of non-transitorycomputer-readable storage media, including, for example, read accessmemory (RAM), read-only memory (ROM), erasable programmable memory(e.g., EPROM and EEPROM), or flash memory. The memory 1002 is configuredto store computer-readable instructions, sensor values, and otherpersistent software elements.

The electronic device 1000 may include control circuitry 1010. Thecontrol circuitry 1010 may be implemented in a single control unit andnot necessarily as distinct electrical circuit elements. As used herein,“control unit” will be used synonymously with “control circuitry.” Thecontrol circuitry 1010 may receive signals from the processor 1006 orfrom other elements of the electronic device 1000.

As shown in FIG. 10 , the electronic device 1000 includes a battery 1014that is configured to provide electrical power to the components of theelectronic device 1000. The battery 1014 may include one or more powerstorage cells that are linked together to provide an internal supply ofelectrical power. The battery 1014 may be operatively coupled to powermanagement circuitry that is configured to provide appropriate voltageand power levels for individual components or groups of componentswithin the electronic device 1000. The battery 1014, via powermanagement circuitry, may be configured to receive power from anexternal source, such as an alternating current power outlet. Thebattery 1014 may store received power so that the electronic device 1000may operate without connection to an external power source for anextended period of time, which may range from several hours to severaldays.

In some embodiments, the electronic device 1000 includes one or moreinput devices 1018. The input device 1018 is a device that is configuredto receive input from a user or the environment. The input device 1018may include, for example, a push button, a touch-activated button, acapacitive touch sensor, a touch screen (e.g., a touch-sensitive displayor a force-sensitive display), a capacitive touch button, dial, crown,or the like. In some embodiments, the input device 1018 may provide adedicated or primary function, including, for example, a power button,volume buttons, home buttons, scroll wheels, and camera buttons.

The device 1000 may also include one or more sensors 1020, such as aforce sensor, a capacitive sensor, an accelerometer, a barometer, agyroscope, a proximity sensor, a light sensor, or the like. The sensors1020 may be operably coupled to processing circuitry. In someembodiments, the sensors 1020 may detect deformation and/or changes inconfiguration of the electronic device and be operably coupled toprocessing circuitry which controls the display based on the sensorsignals. In some implementations, output from the sensors 1020 is usedto reconfigure the display output to correspond to an orientation orfolded/unfolded configuration or state of the device. Example sensors1020 for this purpose include accelerometers, gyroscopes, magnetometers,and other similar types of position/orientation sensing devices. Inaddition, the sensors 1020 may include a microphone, an acoustic sensor,a light sensor, an optical facial recognition sensor, or other types ofsensing devices.

In some embodiments, the electronic device 1000 includes one or moreoutput devices 1004 configured to provide output to a user. The outputdevice 1004 may include the display 1008 that renders visual informationgenerated by the processor 1006. The output device 1004 may also includeone or more speakers to provide audio output. The output device 1004 mayalso include one or more haptic devices that are configured to produce ahaptic or tactile output along an exterior surface of the device 1000.

The display 1008 may include a liquid-crystal display (LCD), alight-emitting diode (LED) display, an LED-backlit LCD display, anorganic light-emitting diode (OLED) display, an active layer organiclight-emitting diode (AMOLED) display, an organic electroluminescent(EL) display, an electrophoretic ink display, or the like. If thedisplay 1008 is a liquid-crystal display or an electrophoretic inkdisplay, the display 1008 may also include a backlight component thatcan be controlled to provide variable levels of display brightness. Ifthe display 1008 is an organic light-emitting diode or an organicelectroluminescent-type display, the brightness of the display 1008 maybe controlled by modifying the electrical signals that are provided todisplay elements. In addition, information regarding configurationand/or orientation of the electronic device may be used to control theoutput of the display as described with respect to input devices 1018.In some cases, the display is integrated with a touch and/or forcesensor in order to detect touches and/or forces applied along anexterior surface of the device 1000.

The electronic device 1000 may also include a communication port 1012that is configured to transmit and/or receive signals or electricalcommunication from an external or separate device. The communicationport 1012 may be configured to couple to an external device via a cable,adaptor, or other type of electrical connector. In some embodiments, thecommunication port 1012 may be used to couple the electronic device 1000to a host computer.

The electronic device 1000 may also include at least one accessory 1016,such as a camera, a flash for the camera, or other such device. Thecamera may be part of a camera assembly which may be connected to otherparts of the electronic device 1000 such as the control circuitry 1010.

As used herein, the terms “about,” “approximately,” “substantially,”“similar,” and the like are used to account for relatively smallvariations, such as a variation of +/−10%, +/−5%, +/−2%, or +/−1%. Inaddition, use of the term “about” in reference to the endpoint of arange may signify a variation of +/−10%, +/−5%, +/−2%, or +/−1% of theendpoint value. In addition, disclosure of a range in which at least oneendpoint is described as being “about” a specified value includesdisclosure of the range in which the endpoint is equal to the specifiedvalue.

The following discussion applies to the electronic devices describedherein to the extent that these devices may be used to obtain personallyidentifiable information data. It is well understood that the use ofpersonally identifiable information should follow privacy policies andpractices that are generally recognized as meeting or exceeding industryor governmental requirements for maintaining the privacy of users. Inparticular, personally identifiable information data should be managedand handled so as to minimize risks of unintentional or unauthorizedaccess or use, and the nature of authorized use should be clearlyindicated to users.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not intended to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. A computing device comprising: a display; anupper housing at least partially enclosing the display; a lower housingrotatably coupled to the upper housing; and a keyboard at last partiallyenclosed by the lower housing and comprising: a set of keys, each key ofthe set of keys including a polymeric keycap; and a biometric input keycomprising: a cap having a front surface gloss value from 1 to 10 asmeasured at 60 degrees and comprising: a transparent ceramic coverdefining a textured front surface; and an opaque coating disposed on arear surface of the transparent ceramic cover; a biometric sensorpositioned below the transparent ceramic cover; a frame positioned belowthe biometric sensor; and a switch positioned below the frame.
 2. Thecomputing device of claim 1, wherein: the biometric input key furthercomprises an anti-reflection coating disposed over the textured frontsurface of the cap and having a thickness from 75 nm to 150 nm; and thetextured front surface defines a surface roughness having an arithmeticmean height (Sa) from 300 nm to 700 nm.
 3. The computing device of claim1, wherein: the opaque coating has a thickness from 1 micron to 2microns and comprises multiple dielectric layers and multiple metallayers.
 4. The computing device of claim 1, wherein: the biometric inputkey further comprises a spring plate positioned below the switch; andthe spring plate is configured to deflect in response to a press inputapplied to the textured front surface of the cap.
 5. The computingdevice of claim 4, wherein: the frame defines a set of protrusions; andeach protrusion contacts a respective portion of the spring plate and isconfigured to apply a force to the spring plate in response to the pressinput.
 6. The computing device of claim 1, wherein: the biometric inputkey further comprises a mechanism coupled to the frame; the mechanism atleast partially surrounds the switch; and the mechanism is configured toarticulate in response to a press input applied to the textured frontsurface of the cap.
 7. The computing device of claim 1, wherein thetransparent ceramic cover is formed from crystalline alumina.
 8. Acomputing device comprising: a first portion comprising a first housingand a display positioned within the first housing; and a second portioncomprising a second housing coupled to the first housing with a hingeand a keyboard, the keyboard comprising: an array of keys; and abiometric power button comprising: a cap including: a transparentceramic cover having a textured front surface configured to diffuselyreflect light; and an inorganic multilayer coating covering a rearsurface of the transparent ceramic cover and configured to absorbvisible light; a biometric sensor positioned below the cap; and anelectromechanical switch positioned below the biometric sensor andconfigured to actuate in response to a press on the biometric powerbutton.
 9. The computing device of claim 8, wherein: the biometricsensor is a fingerprint sensor.
 10. The computing device of claim 9,wherein the biometric power button further comprises a mechanismconfigured to: allow the cap to travel downward in response to the presson the biometric power button; and allow the cap to travel upward inresponse to release of the press on the biometric power button.
 11. Thecomputing device of claim 10, wherein the mechanism includes a scissorsmechanism.
 12. The computing device of claim 8, wherein the texturedfront surface has an arithmetic mean height from 150 nm to 600 nm. 13.The computing device of claim 8, wherein a front surface of the cap hasa gloss value from 1 to 10 as measured at 60 degrees.
 14. The computingdevice of claim 13, wherein a front surface of at least one polymerickey has a gloss value from 1 to 10 as measured at 60 degrees.
 15. Acomputing device comprising: a housing; and a keyboard at leastpartially positioned within the housing, the keyboard comprising: a setof keys; and a biometric button comprising: a cap having a reflectanceof less than 15% over a visible spectrum and including: a sapphire coverdefining a textured front surface; and an anti-reflection coatingdisposed over the textured front surface of the sapphire cover; abiometric sensor positioned below the cap; a support positioned belowthe cap; and a dome switch positioned below the support and configuredto detect a press input applied to the cap.
 16. The computing device ofclaim 15, wherein: the support is electrically conductive; the biometricsensor is a capacitance-based sensor; and the sapphire cover has a glossvalue from 5 to 20 as measured at 60 degrees on the textured frontsurface.
 17. The computing device of claim 15, wherein the cap furtherincludes a multilayer inorganic coating disposed over a rear surface ofthe sapphire cover and having an optical density from 2 to
 5. 18. Thecomputing device of claim 17, wherein the reflectance of the cap rangesfrom 5% to 12% over the visible spectrum.
 19. The computing device ofclaim 17, wherein the cap has an L* value from 20 to
 40. 20. Thecomputing device of claim 19, wherein: the cap has a first color definedby a first L* value; at least one key of the set of keys has a secondcolor defined by a second L* value; and a difference between the firstL* value and the second L* value is less than 10.